Generally, little torque reduction of an engine is performed in shifts such as a N-D shift, a N-R shift, a power-off downshift, and a lift-foot-up (LFU) shift in spite of a present power-off state because of a following tip-in (i.e., depression of an accelerator pedal) state. The small amount of torque reduction is for preparing the following tip-in state, and does not improve shift feel while an idle state is maintained during a shift.
A transmission management system (TMS) requests retardation of ignition timing in order to make a state that the small amount of torque reduction occurs during an engine idle state. In addition, an engine management system (EMS) advances the ignition timing for the following tip-in state.
Therefore, in a conventional art, there is a problem in that the ignition timing retardation request by the TMS and the ignition timing advance by the EMS contradict each other in the idle state.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known in this country to a person of ordinary skill in the art.